We can capture a wider variety of test expectations (timeouts, text-only failures, pixel failures), rather than just skipping files

If we use our infrastructure we can take advantage of tools like the flakiness dashboard upstream as well

Note that it is a non-goal for this project to actually switch webkit.org to our infrastructure; it is sufficient for us to be able to run the chromium.org infrastructure using code that has been upstreamed.

We don't want to move the expectations upstream until we have completed the DRT port - it would be too painful to make changes to one if the other is in a different repository. In particular, we don't want to have to do a WebKit roll to modify test_expectations if a downstream checkin breaks something. This implies that (11), (12), and (13) pretty much need to happen at the same time.